brown



July 21, .1925.

s G. BROWN ELECTRICAL RELAY Filed Aug. 28,

1922 2 Sheets-Sheet 3.

"IVENn n July 21, 1925. 1,546,470

s. G. BROWN ELECIR 1 CAL RELAY Fild Aug. 28, 1922 2 Sheets-Sheet 2 mm aPatented July 21, 1925.

1,546,476 PATENT oFnicE.

SIDNEY GEORGE BROWN, F NOliTH ACTON, ENGLAND.

ELECTRICAL RELAY.

Application filed August 28, 1922. Serial No. 584,736.

To all whom it may conce n Be it known that I, Sirxnr Guonon BRowN, asubject of the King of Great lirit ain, residingat Victoria Road, NorthActon, in the county of Middlesex, l'lngland, have invented certain newand useful Improvements in or Relating "to Electrical Relays, of whichthe following is a specification.

This invention relates to electrical relays adapted for use in theamplification of telephone-speech currents, of the type in which amicrophone is operated by an armature in the form of a vibratory reedbridging the gap between the poles of a receiving polarizedclcctromagnct.

According to this invention the reed operates the vibrating member of adifferential microphone in the local or retransmitting circuit of therelay.

In a suitable construction embodying this invention a pair of receivingcoils of hue wire are wound on laminated cores forming the pole piecesof a. horse shoe permanent magnet, the cores being directed towards eachother, leaving a. gap across which extends the vibrating end or portionof a flat steel reed, the other end of which is firmly secured to abascplate by two screws. 'lhe vibmling reed, at or towards its free end,carries the centre carbon or plate of the dill'ercntial microphone,preferably upon the end of a pin secured on the reed. v 'lhediametcr ofthe centre carbon is preferably about 0.35 inch. The microphone may beof the aperiodic ditl'ercntial type in accordance with the specificationof my British Patent No. 120260.

Oscillations of the current set up variations in the magnetic fieldwhich cause the reed, together with the centre carbon of the microphone,to vibrate. 'lho microphone is connected to a. battery of. say 6 volts,the centre.- carbon, which is subjcct to vibration by the reed, beingconnected to theiiiiddlc point of the battery while. the outer carbons.

or plates are connected to the positive and negative terminals. Or'thcouter plates may be connected through the primary windings of twotransformers to the same battery terminal, the opposite terminal beingconnectedto the central plate. I f a. transformer is used the receivingcircuit for the relayed current is connected through the transformersecondaries.

In order that the said invention may be clearly understood and readilycarried into effect, the same will now be described more fully withreference to the accompanying drawings, inwhich:-

Figure 1 is a side elevation, Figure 2 an end elevation and Figure 3 a.plan of relay mechanism embodying this invention.

Figures 4 to 7 show details of the mechamsm; .i

Figure 8 is a. diagram of the electrical connections; and

Figures 9, 10 and 11 illustrate a. constructional modification of thedevice. 6

Figure 12 is a view, similar to Figure 5, showing a compound microphone.

A is the permanent magnet having pole pieces a on which the tworeceiving coils B are mounted. C is the vibrating reed. D

is the differential microphone. E is a support or standard carrying themagnet, reed, microphone and other members (if the mechanism and itselfmounted upon a. base F., G is a cover titted over the device andattached to the base F.

In the construction illustratcdin' Figures 1 to 8 the magnet A is of theordinary horse shoe shape, but the actual form is immaterial. The polepieces a, which are preferably la'ninatcd, are secured by screws a" onthe cornersof the magnet limbs,which are chamfcred so that the poleproach one another atabout .rig t angles, the adjacent ends being shapedso as to pro- .Vide a plane surface on each side of the narrow gapacross which the reed 0 extends, the reed being parallel of the magnet.

The form of the reed preferred is showh in Figures 6 and 7, the part 0being secured 88 pieces apto the longitudinal axis be adjusted to bringthe pole pieces 0. ac-

curately into position relatively to the reed.

For this purpose the magnet is secured by the aid of the clamping platesH, II provided with clamping and securing screws r bolts. The forwardplates II are secured by the screw bolts h on which are fitted theclamping nuts h, the bolts themselves being screwed into'the support E.The position of the forward endof the magnet is adjusted by these boltsand nuts while for fine adjustment of the magnet pole pieces relativelyto the" reed one of the rear clamping plates H, which are clamped on themagnet near its bend by the screws h", receives the end of a set screwit which passes through ahole in the support E and'is adjusted from theother side of the support, a. strong spring h around the said set screwpressing the end of the magnet away from 'the support. A'slight turn ofthe screw it allows of very close adjustment of the pole pieces arelatively to the reed. -A- small collar 72. on the head of the setscrew can be filed away at one side after adjustment and a -smallscrewed stud h provided on the support E to prevent accidental turning;

The microphone D comprises a solid block casing 11 secured on thesupport E by the "screw d and the pegs d. Themicrophone is preferably ofthe aperiodic differential t pe described in the specification of myritish Patent No. 120260. and comprising a central carbon plate d lyingin the granule filled cell d without attachment to any part of themicrophone and supported entirely between the two granule layers and theside lining d, which may be of pile fabric such as velvet, allowing offree axial movement of the carbon plate without side displacement. Thegranules are packed on both sides of the centre plate at and betweenthe.

outer plates d". r

The centre plate d: of the microphone is rigidly connected throughtherod d to the tongue 0 on the end of the reed C so that any vibrationofthe reed due to the reception of telephone currents in the coils B istransmitted to the centre plate of the microphone, a movement in onedirection causing increased compression in the granules at that side ofthe plate and a loosening of the granules at the other side so that theresistance is varied in opposite directions at the two sides of themicrophone. The diameter of the centre plate (1 is preferably about 0.35inch, but the precise dimensions would vary with the general size of theinstru r ment and the work for which it is adapted.

It is necessary for the reed C to be pre vented from coming in contactwith the poles a of the magnet as the reed might stick to the poles. Atthe same time the adjustment must be made so that the reed is as closeas possible to the (poles .without actual ontact bein permitte at anytime. To prevent'the risfi of contact a small ad justable stop isprovided in the form of a screw J mounted on the magnet poles. Themounting may conveniently be arranged by fitting the screw sto J in thehead j of the clamp screw j whic clamps the two small a little behindthe front faces as shown in Figures land 2. By adjusting the screw stopJ, the end of which lies just behind the tongue 0 of'the reed, the reedis prevented from accidentally meeting the faces of the pole pieces, butis allowed to approach them very closely so as to reduce the air gap toa minimum.

A suitable arrangement of circuit for the microphone relayis shown inFigure 8, which is a diagrammatic plan. The two coils B are connected tothe terminals K, to which the receiving circuit is connected, while thecentre plate (1 of the microphone is connected to one battery terminal Land the outer plates d are connected through the primary trans-formercoils Z to the other "battery terminal L. This is given as an example ofthe differential microphone connections, but the invention is notconfined to any special method of connecting up the microphone. The{coal or retransmitting relay circuit is connected to the terminals M towhich the secondary coils m are connected as shown in the diagram. Theform of microphone shown in Figure 12 is substantially the same as thatillustrated in Figure 5, except that the' microphone is divided into twocells d, each of which has a central carbon plate 01- supported betweenthe granule layers in the cells and lying within the side lining d; boththe central plates (i being rigidly mounted on the rod (1. This compoundmicro hone is especially useful in connection wit a loud. speiakingtelephone system.

In Figures 9, 10 and 11 a modified construction is shown of smaller sizeand more compact form, designed more especially for use as an amplifierin aural apparatus for the deaf, but adapted f 1' other purposes wherean amplifier of em ll size is required. The principle of the modifieddevice is identieal with that already described, but for convenience thedevice is circular and comprises a part circular magnet A mounted on thecircular supporting baseE to which it is-secured by the screws a, whichalso serve to fix the pole pieces a, these pole pieces projectingtransversely across the end of the magnet and approaching close to eachother'at the centre to leave a small air gapbridged bgr the reed C whichis secured at one end by the'scrmvc on the post 0 of the base E The poepieces a may be in the form of a single plate with a slot cut at thecentre to form an air gap and leaving narrow bridging bars at each side,

To allow for fine adjustment-1' between the reed and the magnet polesthe post a is made in a separate piece from the base E but is fixed byriveting in the base and can yield slightly in a resilient manner underthe pressure of the small adjusting screw a secured in the base underthe arm a of the post. By adjustment of this screw the angle of the postand the reed can be adjusted sufficiently to give the reqluired fineadjustment of the reed relative the pole pieces by the screw stop Jcorresponding to the screw stop J of the previously describedconstruction, the screw stop being carried by the small 'bracket c' onthe base E.

The microphone D is of similar type to that already described,but ofmuch smaller and lighter construction and is mounted on the back of thebase E which is recessed to receive the casing, the latter being screwedupon the supporting plate d of insulating material, the plate lying in arecess in the base E. The rod d connected to the centre plate of themicrophone D is attached to the part c of the rated G and not to thetongue 0" as in the previous case. The microphone terminals areindicated at L corresponding to the terminals L of the vpreviouslydescribed construction.

What I claim and desire to secure by Letters Patent of the United Statesis :-5-

1. In an electrical relay, a receiving polarized electromagnet havingclosely approaching pole pieces, a vibratory armature reed bridging thega between the lee, a differential microp mm in the loca orretransmitting circuit, means for connecting the vibratory member ofsaid microphone to the said reed, and'means for effecting fineadjustments between the electromagnet and the reed.

2. In an electrical relay, a receiving polarized electromagnet havingclosely approaching pole pieces, a vibratory armature reed br dging thegap between the lee, a differential microp one in the locaorretransmitting circuit, a rod rigidly connecting the vibratory member ofthe microphone to said reed, and means for effecting fine adjustmzritsbetween the eiectromagnet and the re 3. In an electrical relay areceivinglpolarized electromagnet, thepoles of whic closely approacheach other, a stationary support, a differential microphone, the casingof which is fixed on said support, a vibratory armature reed fixed atone end and bridging the gap of the magnet poles and connected rigidlyto the vibratory member of the differential microphone, and a fineadjustment means for the. said electromagy to-the ma et poles.-. Thereed is prevented from touc mg .ferential microp ones and and a fine adustment means between the said electrofnagnet and its support by meansof which its poles can be adjusted closely to the reed.

I 5. In an electrical relay,'a(permanent ma net of horseshoe type provied with close y approaching le ieces, receiving coils mounted on 't e p0e pieces, a stationary support for the magnet, a carrying membersecuring the magnet towards its pole end to the said support, a mountingfor the rear end of the magnet provided with a screw adjustmentbetweenthe support and the magnet by which the position of the m net poles canbe accurately adjusted by slight angular movement of the magnet, astationary differential microphone, and a vibratory armature'reed firedtowards its free end to the vibratory member ofthe differentialmicrophone and secured to the stationary support at the other end.

6. In an electrical relay, a rmanent ma net of horseshoe type provi edwith close approaching ole ieces, receiving eoi s mounted on t e po epieces, a 'stationary support for the magnet, acarrying member securingthe magnet towards its pole end to the said support, a mounting for therear end of the magnet provided. with a screw adjustment between thesupport and the magnet by which the position of the ma et polescan beaccurately adjusted by slight angular movement of the magnet, a.stationary microphone, and a vibratory armature reed fixe towards itsfree end to the vibratory member of the microphone and secpred to thestationary support at the other en 0 i j 7. In an electrical relayareceiving polarized electroma pole pieces, avi ratory' armature reedridgmg t e gap between the poles, a compound microphone com rising apluralit of dif means or rigidly sccurin the central vibratory membersof the sai microphones together and to the armature reed.

SIDNEY GEORGE BROWN.

t having closely ad acent

